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TRANSCRIPT
Linking CMEs to Associated Solar Phenomena
Peter Gallagher, Pietro Zucca, Eoin Carley
School of Physics
Trinity College Dublin
Ireland
Göttingen Magnetischer Verein
• Trinity College Dublin was a site of Gottingen Magnetic
Union (1836-1841).
• Magnetic measurements
up to every 5 mins.
• Led to magnetic crusades
by Edward Sabine and
Humphrey Lloyd.
• Sabine (1852): Sunspot cycle identical to geomagnetic
cycle.
Ballistic Propagation Model
• Search time window:
• Search PA window: PA ± ΔPA
t f ± Dt f = t i -Ri - Rf
v ± Dv
Input Property Input Parameter
Initial time τi
Initial distance Ri
Final distance Rf
Velocity range v ± Δv
Position angle PA
Width (PAN – PAS) / 2
HI1 -> COR2
• Search time window:
• Search PA window: PAfit ± ΔP
tCOR2 ± DtCOR2 = t HI1 -RHI1 - RCOR2
vSW ± DvSW
Input Property Input Parameter
Initial time τi
Initial distance 12 RS
Final distance 2 RS
Velocity range 200-600 km/s
Position angle PAfit
Width (PAN – PAS) / 2
Case Study
• ***** HI2 Parameters *****
• HI2 Start Time : 29-Jul-2007 07:30:00.000
•
• ***** COR2 Search Parameters *****
• COR2 Start Time: 28-Jul-2007 18:37:46.668
• COR2 End Time : 29-Jul-2007 05:05:12.500
• Window (hours) : 10.457176
• COR2 PA-N : 240.000
• COR2 PA-S : 300.000
•
• ***** Flare Search Parameters *****
• Flare Start Time: 28-Jul-2007 17:25:22.918
• Flare End Time : 28-Jul-2007 18:01:34.793
• Window (mins) : 36.197919
Case Study
28-Jul-2007
18:37
29-Jul-2007
05:05
28-Jul-2007
17:25
28-Jul-2007
18:01
29-Jul-2007
07:30
29 A 300 240
Case Study
CME Candidate: 29-Jul-2007 01:37 | PA 275o | Width 96o | 625 km/s
S
180 N
360
W
270
E
90
Search PAs: 240-300 Search Times: 28-Jul-2007 18:37
29-Jul-2007 05:05
Case Study
28-Jul-2007
18:37
29-Jul-2007
05:05
29-Jul-2007
01:37
28-Jul-2007
17:25
28-Jul-2007
18:01
29-Jul-2007
07:30
29 A 300 240
Case Study
28-Jul-2007
18:37
29-Jul-2007
05:05
29-Jul-2007
01:37
28-Jul-2007
17:25
28-Jul-2007
18:01
None None NA 29-Jul-2007
07:30
29 A 300 240
Improved Inverse Tracking
• Use variable velocity profile
• Drag-based propagation model to obtain v(R)
• SOTERIA Drag-Based Model
http://oh.geof.unizg.hr/DBM/dbm.php
• E.g Vršnak et al. (2010)
t f = ti -1
v(R)dR
Ri
R f
ò
Modelling of CME Motion
• Simple model for CME propagation in heliosphere
• Numerical integration gives v( r ).
• Vršnak et al. (2002), Reiner et al. (2003), Tappin (2006).
rdv
dt= -
1
2rDv2ACD
Coronal Mass Ejections
Coronal Waves
Radio Bursts
How are these related?
How are shocks formed?
[email protected] Maloney & Gallagher (2011)
CME-Driven Shock Properties
Shock standoff distance
(Δ) varies linearly with
height.
Linear extrapolation
gives Δ ~ 40 Rsun at
Earth.
Can give improved
estimate of shock
arrival time at Earth.
0.01 MHz
400 MHz
Fre
quency (
MH
z)
~2 hours <2 minutes
Birr, STEREO and Nancay Radio Spectra
Carley et al. (2013)
How do we find shock heights?
h(ne)
ne(h) = n0e-h/H
fp[Hz] @ 9000 ne[cm-3]
Frequency(t)
Density(t)
Height(t)
ne(f)
h(ne) Example model:
Plasma frequency:
Type II Height Problem
=> Given frequency gives single density but model dependent heights!
1.4 Rs 2.1 Rs
fp[Hz] @ 9000 ne[cm-3]
Solution: Data-constrained Alfven Maps
vAlfven (x, y) =B(x, y)
mmpne(x, y)
Electron density maps
(SDO/AIA and SOHO/LASCO)
Potential magnetic
field model
(PFSS)
94Å 131Å 171Å
193Å 211Å 335Å
Densities in low corona (<1.3 RS)
Aschwanden et al. (2011)
SDO/AIA
Intensity (T)
Emission Measure (T)
Density
Intensity (T)
Densities in high corona (>2.5 RS)
Brightnessµ ne(r)G(r, s)dsLOS
ò
SOHO/LASCO Intensity Electron Density
Two-component Density Model
• Spherically symmetric corona in hydrostatic equilibrium:
• At r < r0 , reduces to plane parallel solution
• Combine spherically symmetric and plane parallel
Zucca et al. (2014)
Alfvén Speed Map
2 RSun
150 300 600 1250 2500 5000
Alfven speed
local min
Shock location
Alfven speed (km/s)
Zucca et al. (2014)
Conclusions
• Linking heliospheric to coronagraph features
– Ballistic model works well
• Linking coronagraph to low corona and surface
– Challenging - deflection important
– Activity in EUV images key
• Linking CMEs to IP and coronal Type II bursts
– Difficult without radio images
– Density and Alfven maps key
